Methine dyestuffs



Patented July 15, 1952 7 METHINE DYESTUFFS 7 Harry Derek Edwards, London, and John David 1 Kendall, Ilford, England,

assignors to Ilford Limited; Ilford, England, a British company 1 Na Drawing,

' ,1948,"Seria1' No.

' cation August 28, 1950, Serial No.

original'application January 15,

2,554. Divided and this appli- Great Britain'January 24, 1947 3 Claims. '(Cl. 2 -240) This invention relates to the production of new organic compounds which are valuable photographic sensitising dyes, and isdivided from -ap-' plication Serial No.'2,554 filed-January 15, 1948; now Patent No. 2,533,233. 1

According to application Serial No. 2,554 compounds of the general Formula 1 Where R as an alkyl or aralkyl group are prepared by reacting carbon disulphide With the dry alkalimetal derivative ofmalodinitrile and alkylating or aralkylating the product with an alkyl or aralkyl salt or ester.

These compounds may be referred to as 518-- dicyano ketene dialkyl or diaralkyl-mercaptoles. jf The re actifcnwith carbon disulphide can con veni'eritly "be effected with the malodinitrile in suspension in diethyl ether, though otherlinert solventsj can be used. As alkali-metal, metallic sodium is the most convenient toiuse Alkyl ation may be effected, for example, with methyl; ethyl and higher alkyl halides'and the iodides arepare ticularly suitable. Other alkylatingagents which maybe used are dialkyl'sulphatBS, e; g. dimethyl sulphate and diethyl sulphate, alkyl p-toluene sulphonates, e. g. methyl or ethyl ptoluenesulphonates, or alkylene dihalides, e. g. ethylene dibromide and trimethylene dib-romide. The alkyl group of the alkylating agent may be substituted so that other alkylating agents which may be used'a-re chloracetic esters; Aralkylating agents are benzyl halides or sulphates.

The reaction with the carbon disulphide is best efiected by allowing the reagents to stand together at room temperature and the alkylation or aralkylation is best effected by warming the reagents together.

According to this invention a compound of generalFormula I is reacted with an .alkyl or arallgyl quaternary Isalt of a five-membered or six-mem berd heter'o'cycli'c nitrogen compound containing a reactive methylene group. in a or v position to the heterocyclic nitrogen atom, i. e. with a componndof'the 'generalForm'ula II:

In this formula R1 represents an alkyl or -ara1- kyl group, e. g. methyl, ethyl, .propyl, butyl or higher alkyl containing from to 18 carbon atoms,

benzyl and naphthylmethyl, R2 represents a hydrogen atom or a hydrocarbon group,- e. g. an alkylor aralkylgroupsuch as any of those listed in respect of R1, or an aryl group such-asphenyl or naphthyl, X represents an acid radicle, e. g. halide (chloride, bromide or iodide), sulphate,

perchlorate or p-toluene sulphonate, D represents the residue of a five-membered or six-membered heterocyclic nitrogen ring, and n is nought or 1. Typical ring systems which may be present are thiazole, oxazole, selenazole and the polycyclic members of these series, e. g. benzthiazole, benzoxazole and rbenzselenazole, thiazoline, selenazoline, oxazoline, pyridine, quinoline, lepidine and indolenine. 3

The reaction takes'place with the elimination of the elements HX and RSH yielding products ofthe-general Formula III: j 1

V ."J ':L R2 SR 1l|r oH=oH),.- E= 'Jx-o=o v n I R; I 7 UN in i The reaction with thelduaternary saltt of heterocyclic nitrogencompound is preferablyseffected inthe presence of a base, e. g. pyridine;

diethylamine, triethylamine or. sodium acetate. .in.

ethyl alcohol. =-The dyestufis of general Formula 111- arese'nsitisin'g dyes for photographic silver halide emul-x.

sions," and thisinvention includes silver halide photographic emulsions .and particularly silver chloride, silver bromide, silver chlorobromide and silver iodobromide emulsions containing the said dyestufis. t The following examples illustrate the invenion:

EXAMPLE 1 Preparation fob the compound of the formula I. .CH:

":85, gms. of )sm-dicyan'oketene' diethyl mer captoleiwas fused at (Ll-for 2 hours'with'7L5j gmsi oi I-methyl b'enzthiazole and 9.3 gms'fof methyl p-toluene sulphonate; Ten cc. of pyridine was added and the "mixture boiled under reflux for 12 minutes. On pouring thefreaction mixture intowater the desired product separati m. it filtered off and recrystallised from methyl-alcohol EXAMPLE 2 Preparation of the compound of the formula 2.5 mols of Z-methyl-benzoxazole ethiodide were boiled gently under reflux for 15 minutes in ethyl alcohol solution with 2 mols of pfi-dicyano ketene diethyl mercaptole and 5 mols of triethylamine. On'dilution with water the dye precipitated and on recrystallisation from methyl alcohol it wasobtained as red crystals, M. Pt. 151 C.

Preparation of the compound of the formula One mol of 2-methyl-p-naphthathiazole and one mol of methyl p-toluene sulphonate were fused together at 100 C. fo'r'l5 hours; One mol of fifi-dicyano ketene diethyl mercaptole was added and the mixture boiled gently for half an hour under reflux with ethyl alcohol and one mol of triethylamine. On pouring the reaction mixtime into. water the requireddyestuff was precipitated. After separation and recrystallisation from ethyl alcohol it was obtained ascrystals melting at 220 C.

This. dyestulf was incorporated in agelatino silver iod'obromide emulsion and imparted a band of sensitivity extendingto aboutz5900A. with a'maximum at about 5500 A.

EXAMPLE! J Preparation of the compound of the formula;

SCH: ON

=cH-o=o \CN One mol of ce-dicy'ano' k etene dimethyl mercaptole was boiled gently under reflux for minutes in ethyl alcohol solution with one mol of lepidine methiodide and one mol of triethylamines The mixture became a bright magenta colour "and on dilution withewater the required dyestutf precipitated out.,.,' On recrystalli'sfaltion from enzene the dye was obtained as red needles with the blue reflex, M. Pt;. 22 1 c. f.

This dyestufli when incorporated in a gelatino silver iodobromide emulsion, imparts aband'of ensitiyity extending to 59005. V

4 EXAMPLE 5 Preparation of the compound of the formula One mol each of pp-dicyano ketene diethyl mercaptole, 2-methylthiazoline and methyl ptoluene sulphonate were fused together at 100 C. for two hours. The mixture became yellow,

ethyl alcohol was added and the whole boiled carefully diluted and allowed to stand for several hours during which the dyestufl. crystallised out in long needles. On recrystallisation from methyl alcohol it was obtained as crystals melting at 161 C.

This dyestufi, when incorporated in a gelatino silver iodobromide emulsion, imparts a band of sensitivity extending'to about 5300 A. with maximum at about 4700 A.

EXAMPLE 6 Preparation of the compound of the formula .One mol of Z-methyl benzthiazole ethiodide sensitivity extending, to 5500!}. with a maximum at'5000 A.

EXAMPLE '1 Preparation of the compound of the formula.

r om: CN 7 ;=Q(. 1 N a ch: "Oine inol each-of flB-"dicyano ketene mercaptole; 2-ethyl benzthiazole and methyl p toluene-isulphonate were-j fused together at fo r 2 hours, the mixture becomingdeep' orange. Asmall amount .of' ethyl alcoholj and one mol of triethylamine were added and themixture boiled gently under reflux for 15 minutes. On cooling and diluting with-water the required product separated in red crystals with a gold reflex. On recrystallisation from ethyl alcohol, in which the product is onlymoderately soluble, the crystals of the product melting at 187913.. were obtained. 7 J v g- What we claim is: Process for the production of dyestuffs which comprises reacting a Bfl-dicyano ketene dialkyl mercaptole of the general formula:

CN S-alkyl C=C/ ,CN/ Salkyl with a compound of the general formula:

N=(CHCH),.=(IJ-GHR, R1 \X where R1 is selected from the class consisting of alkyl and aralkyl groups and R2 is selected from 1 the class consisting of the hydrogen atom and hydrocarbon groups.

where R1 is selected from the class consisting of 3 alkyl and aralkyl groups and R2 is selected from the class consisting of the hydrogen atom and hydrocarbon groups, in the presence of a basic condensing agent.

where R and R1 are each selected from the group consisting of alkyl and aralkyl groups, Hz is selected from the group consisting of the hydrogen atom and hydrocarbon groups, D is the residue of a heterocyclic nitrogen nucleus and n is selected from nought and. 1.

HARRY DEREK EDWARDS. JOHN DAVID KENDALL.

REFERENCES CITED The following references are of record in the file of this patent:

.UNITED STATES PATENTS Number Name Date 2,166,736 White et a1 July 18, 1939 2,263,749 White et a1 Nov. 25, 1941 2,320,654 Riester June 1, 1943 2,322,015 Hamer et a1 June 15, 1943 2,338,782 Riester Jan. 11, 1944 2,340,882 Kendall Feb. 8, 1944 2,353,164 Kendall et a1 July 11, 1944 OTHER REFERENCES Chemical Abstracts 1623101 (Abstract of Brit. Med. Journal, 1922, I 514-515).

Chemical Abstracts 19:530 (Abstract of Proc. Roy. Soc., London, 96B 317-333, 1924). 

1. PROCESS FOR THE PRODUCTIONOF DYESTUFFS WHICH COMPRISES REACTING A BB-DICYANO KETENE DIALKYL MERCAPTOLE OF THE GENERAL FORMULA: 